msc: fix f_tc_mt_crcx_ran_reject(): properly handle Iu-ReleaseCommand

Previous commit [1] uncovers a problem in f_tc_mt_crcx_ran_reject():
this function uses as_clear_cmd_compl_disc(), which is expecting
A-interface (GERAN) specific BSSMAP Clear Command.  The Iu-interface
(UTRAN) specific RANAP Iu-ReleaseCommand is not handled at all.

The testcase was passing so far due to a bug in as_optional_cc_rel(),
which would unblock the alt-statemtnt on receipt of CC RELEASE, so
that we would never respond to RANAP Iu-ReleaseCommand.

Let's derive a new altstep from f_expect_clear() and use it.

Change-Id: Idd679bbf720a56a76cf37ab414b1e6d90e53278b
Related: [1] I0143b4d33b1ebe4cce99c09018540524c4626eec
---
M msc/BSC_ConnectionHandler.ttcn
M msc/MSC_Tests.ttcn
2 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/msc/BSC_ConnectionHandler.ttcn b/msc/BSC_ConnectionHandler.ttcn
index 0a30114..be12fae 100644
--- a/msc/BSC_ConnectionHandler.ttcn
+++ b/msc/BSC_ConnectionHandler.ttcn
@@ -1966,7 +1966,7 @@
 	setverdict(pass);
 }
 
-/* expect a clear command */
+/* expect a clear command (for GERAN only!) */
 altstep as_clear_cmd_compl_disc() runs on BSC_ConnHdlr {
 	var PDU_BSSAP bssap;
 	[] BSSAP.receive(tr_BSSMAP_ClearCommand) {
@@ -1987,23 +1987,28 @@
 		}
 }
 
+/* expect a BSSMAP Clear Command (for GERAN) or an Iu-ReleaseCommand (for UTRAN) */
+altstep as_expect_clear() runs on BSC_ConnHdlr {
+	[g_pars.ran_is_geran] as_clear_cmd_compl_disc();
+	[not g_pars.ran_is_geran] as_iu_release_compl_disc();
+}
+
 function f_expect_clear(float t := 5.0, boolean verify_vlr_cell_id := true) runs on BSC_ConnHdlr {
 	timer T := t;
 
 	T.start;
 	alt {
-	[g_pars.ran_is_geran] as_clear_cmd_compl_disc() { }
-	[not g_pars.ran_is_geran] as_iu_release_compl_disc() { }
+	[] as_expect_clear() {
+		if (verify_vlr_cell_id) {
+			/* Now the conn is gone, but the VLR reflects the cell ID */
+			f_verify_vty_lac_ci();
+		}
+		}
 	[] T.timeout {
 		setverdict(fail, "Timeout waiting for ClearCommand/Release");
 		mtc.stop;
 		}
 	}
-
-	if (verify_vlr_cell_id) {
-		/* Now the conn is gone, but the VLR reflects the cell ID */
-		f_verify_vty_lac_ci();
-	}
 }
 
 function f_create_bssmap_exp_n_connect(integer targetPointCode) runs on BSC_ConnHdlr {
diff --git a/msc/MSC_Tests.ttcn b/msc/MSC_Tests.ttcn
index 7e8f467..101d632 100644
--- a/msc/MSC_Tests.ttcn
+++ b/msc/MSC_Tests.ttcn
@@ -1752,8 +1752,8 @@
 		repeat;
 		}
 	[] MGCP.receive { repeat; }
-	[] as_clear_cmd_compl_disc();
-	[] as_optional_cc_rel(cpars);
+	[] as_optional_cc_rel(cpars); /* repeats internally */
+	[] as_expect_clear() { setverdict(pass); }
 	}
 }
 testcase TC_mt_crcx_ran_reject() runs on MTC_CT {

